Monday, January 6, 2014

Searching the Internet for evidence of time travelers

Wibbly-wobbly timey-wimey.
Two physicists from Michigan Technological University, Robert J Nemiroff and Teresa Wilson, have written an article, Searching the Internet for evidence of time travelers.

Time travel has captured the public imagination for much of the past century, but little has been done to actually search for time travelers. Here, three implementations of Internet searches for time travelers are described, all seeking a prescient mention of information not previously available. The first search covered prescient content placed on the Internet, highlighted by a comprehensive search for specific terms in tweets on Twitter. The second search examined prescient inquiries submitted to a search engine, highlighted by a comprehensive search for specific search terms submitted to a popular astronomy web site. The third search involved a request for a direct Internet communication, either by email or tweet, pre-dating to the time of the inquiry. Given practical verifiability concerns, only time travelers from the future were investigated. No time travelers were discovered. Although these negative results do not disprove time travel, given the great reach of the Internet, this search is perhaps the most comprehensive to date.

(ht: Maureen Eckert)

Saturday, February 23, 2013

Roko's basilisk - RationalWiki

Roko's basilisk - RationalWiki

Roko's basilisk is a proposition suggested by a member of the rationalist community LessWrong, which speculates about the potential behavior of a future godlike artificial intelligence. According to the proposition, it is possible that this ultimate intelligence may punish those who fail to help it, with greater punishment accorded those who knew the importance of the task. This is conventionally comprehensible, but the notable bit of the basilisk and similar constructions is that the AI and the person punished have no causal interaction: the punishment would be of a simulation of the person, which the AI would construct by deduction from first principles. In LessWrong's Timeless Decision Theory (TDT), this is taken to be equivalent to punishment of your own actual self, not just someone else very like you.


In short order, LessWrong posters began complaining that merely reading Roko's words had increased the likelihood that the future AI would punish them — the line of reasoning was so compelling to them that they believed the AI (who would know they'd once read Roko's idea) would now punish them even more for being aware of it and failing to donate all of their income to institutions devoted to the god-AI's development. Thus, even looking at this idea was harmful, lending Roko's proposition the "basilisk" label (after the "basilisk" image from David Langford's science fiction stories, which was in turn named after the legendary serpent-creature from European mythology that killed those who saw it). The more sensitive on LessWrong began to have nightmares.

Thursday, February 21, 2013

Indefinite Survival Through Backup Copies

Indefinite Survival Through Backup Copies

Anders Sandberg & Stuart Armstrong

abstract: If an individual entity endures a fixed probability of disappearing ("dying") in a given fixed time period, then, as time approaches infinity, the probability of death approaches certainty. One approach to avoid this fate is for individuals to copy themselves into different locations; if the copies each have an independent probability of dying, then the total risk is much reduced. However, to avoid the same ultimate fate, the entity must continue copying itself to continually reduce the risk of death. In this paper, we show that to get a non-zero probability of ultimate survival, it suffices that the number of copies grows logarithmically with time. Accounting for expected copy casualties, the required rate of copying is hence bounded.

Friday, February 8, 2013

Multimodal exploration of the fourth dimension

Multimodal exploration of the fourth dimension
Hanson, A. & Zhang, H.

DOI : 10.1109/VISUAL.2005.1532804

abstract: We present a multimodal paradigm for exploring topological surfaces embedded in four dimensions; we exploit haptic methods in particular to overcome the intrinsic limitations of 3D graphics images and 3D physical models. The basic problem is that, just as 2D shadows of 3D curves lose structure where lines cross, 3D graphics projections of smooth 4D topological surfaces are interrupted where one surface intersects another. Furthermore, if one attempts to trace real knotted ropes or a plastic models of self-intersecting surfaces with a fingertip, one inevitably collides with parts of the physical artifact. In this work, we exploit the free motion of a computer-based haptic probe to support a continuous motion that follows the local continuity of the object being explored. For our principal test case of 4D-embedded surfaces projected to 3D, this permits us to follow the full local continuity of the surface as though in fact we were touching an actual 4D object. We exploit additional sensory cues to provide supplementary or redundant information. For example, we can use audio tags to note the relative 4D depth of illusory 3D surface intersections produced by projection from 4D, as well as providing automated refinement of the tactile exploration path to eliminate jitter and snagging, resulting in a much cleaner exploratory motion than a bare uncorrected motion. Visual enhancements provide still further improvement to the feedback: by opening a view-direction-defined cutaway into the interior of the 3D surface projection, we allow the viewer to keep the haptic probe continuously in view as it traverses any touchable part of the object. Finally, we extend the static tactile exploration framework using a dynamic mode that links each stylus motion to a change in orientation that creates at each instant a maximal-area screen projection of a neighborhood of the current point of interest. This minimizes 4D distortion and permits true metric sizes to be deduced locally at any point. All these methods combine to reveal the full richness of the complex spatial relationships of the target shapes, and to overcome many expected perceptual limitations in 4D visualization.


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